Steering column-mounted levers for automotive vehicles are often provided with switches for controlling remote vehicle systems such as high-beam headlights, trailer lights, overdrive functions, wipers, and cruise controls, to name a few. The switches must be wired through the levers, with varying degrees of difficulty.
Steering column-mounted gear shift levers, for example, are particularly difficult to wire. They are typically fashioned with an ergonomic curved or bent shape, having one or more sharp bends between the operator knob end and the inner end connected to the steering column. Shift levers often have a switch in the operator knob, for example a pushbutton switch or a rotatable switch, for operating remote vehicle systems like those listed above. Electrical wiring from the switch runs through a hollow bore formed in the shift lever for this purpose.
The shift lever is subject to significant stress during shifting operations, and must be strongly built. The typical switch-equipped shift lever uses a relatively thick-walled steel tube as its core, with the bore open at the knob end and plugged or blind-bored at the column end to provide structural support for a mechanical connection to the steering column. The tubular steel core is formed into the bent shape of the lever, and then covered with a decorative and user-friendly plastic material by over-molding a plastic sheath onto the steel. An angled wire passage is drilled or otherwise formed through the wall of the steel tube at or near the closed column end, such that the wiring from the knob-mounted switch can run through the shift lever bore and exit near the column end at an angle to the shift lever axis.
The typical shift lever, although strong, is accordingly difficult and expensive to manufacture. The steel tube is often formed, for example, by gun-drilling a bore in a solid steel billet. The shape-forming process requires powerful machinery. Molding a plastic cover onto the formed steel core requires more machinery and manufacturing steps, and delays the wiring assembly until the heat from the over-molding process has dissipated. Finally, fishing the electrical wires from the knob assembly through the sharp bends of the shift lever bore and out the small, angled wire outlet at the closed steering column end is labor-intensive.
To address the foregoing problems, my co-pending U.S. application Ser. No. 11/160,793 discloses a switch-equipped shift lever with a solid core and a pre-molded plastic cover or sheath formed in two or more clamshell-type sections radially mated over the core, and with an open wiring raceway exposed on the interior of at least one of the sheath sections. The switch wiring can accordingly be mounted on the interior of the clamshell section as, or before, the sheath sections are secured to the shift lever core.
Other types of switch-equipped levers can be found mounted on steering columns, for example turn signal lever arms that include switch knobs for purposes such as switching between high and low headlight beams, or operating front or rear wipers. These other switch-equipped levers tend not to require the strength of a shift lever, and may be easier to wire as a result of having shorter, straighter, hollow shafts without reinforcing structural cores. Wiring the switches on such levers is nevertheless a relatively time-consuming task, and still requires providing a wire pathway through the lever arm or shaft.